Warming up vehicles in winter

[5MilesBack]

It's interesting that when I start my 2021 tundra or 2012 highlander in the dead cold the RPMs stay at 1200 or so until the engine is fully warm - then they drop to 600-700.

Don't all vehicles do that? My '89 Toyota 4x4 does the same even in the summer. It will high idle until it reaches a certain temp, then drop back to 800 or so. My Tundra does the same, but to a lower idle.

 

[stanginthe11s]

yes, all vehicles do that since the mid 80's. its mostly based on coolant temperature. roughly 140 degrees. but the computer monitors many things so it can change if certain parameters are not met.

 

[black dawg]

not really true. without getting into it, basically if you have oil in your cylinders you have bigger issues.
the fuel that comes in hot or cold is still atomized to some degree and the fuel does not get pushed to the walls. incomplete burn gets pushed out the exhaust.

honestly, in today's world it doesn't really matter much. it doesn't hurt the motor either way. other than lubrication to the bearings, the engine doesn't care.
transmission fluid flows well hot or cold, and yes idling still raises the temp of the trans.
I warm up my car because I have leather seats and a bad back.

Not sure where I said anything about oil above the rings?

I do agree that in most cases it really does not matter much. And yes I warm up everything atleast somewhat. And like I said above, with most modern fuel injection, even stuff clear back to the mid 90s, I really think that cold idling causing cylinder washing and fuel contaminated oil is really overblown.

 

[Greyinggrayling]

My 2019 Buick gets its block heater plugged in at night when below 20. My auto start is not at full rpm - I still get in it and have to start the car normally. The engine turns over, etc. So, I don’t know what that low-power auto start is exactly, but motor is running, there is exhaust, and the cabin heat is about half-power.

Auto-start/pre-heating is not illegal in Anchorage, as someone stated. Leaving the keys in your car with the engine running is illegal. A keyless auto start is fine.

 

[Wrench]

Pistons can expand up to about a half thou every 25*.

With manufacturers wanting to make money on maintenance....I'm good with letting some heat soak.

My family owned an automotive machine shop and cold starts were always considered the highest wear time. There's a reason thermostats hold engine temps up.....it's not to keep your heater hot, it's because less wear occurs at operating temp.

Zero weight oils help....but they also tend to encourage long drain intervals and silicate contamination doesn't care what weight oil you use.

Now in the case of dpf rigs....those need to be hot or not running. Idle is hell on them.....especially when its cold.

 

[coloyooper]

Always warm my vehicle up. Can’t see how it would be bad for the vehicle to run. Don’t care if I’m polluting the ozone, and I live in an area where the least of my concerns is someone trying to jack my vehicle at 5am before work

 

[Wrench]

The article talks mainly about the engine . Wonder about the transmission when its -30° ?

When I worked in Prudhoe bay they had to glue the coolant hoses on because the trucks could see a 270* temp swing and the clamps wouldn't always hold when it was super cold. Oils were swapped to arctic grade.

 

[Mk44]

+1 for warming up vehicle in the winter.

 

[GSPHUNTER]

The only reason I ever warmed mine, was to warm up enough to get heat in passenger compartment.

 

[stanginthe11s]

Because engines running cold can have some incomplete combustion, leaving fuel on the cylinder walls. This fuel washes away oil on the cylinder walls. This is the theory, and for sure does happen on some scale

Not sure where I said anything about oil above the rings?

you stated fuel washes away oil on the cylinder walls. therefore, there must be oil, no?
I understand your opinion on cylinder washing, though it doesn't really happen like many believe. it takes a very large amount of fuel to truly cause cylinder washing.
on a correctly running engine the unburnt fuel gets expelled out through the exhaust which creates higher emissions. if the tune is not correct, and you have extreme low temps you could create a situation where there's potential to wash cylinders simply because gasoline is not flammable.

anyway, it was not a personal attack. and there's a ton that goes into all of this, some on a molecular level but I'm not trying to go there.​

 

[DenverCountryBoy]

Long enough for the seat warmer to do it's thing.

 

[summs]

I'll take OP's side. I used to let everything idle for a bit, now with gas cars, when the auto choke finishes, i'll start to drive. Slowly until well onto the thermostat.

The diesel truck, I used to be an let it idle guy, but it's pointless. Common rail or newer cummins CAN NOT get warm at idle. They actually cool down between injection events. If I have to wait for the grid heater light to go out, I high idle the truck until the grid heater stops cycling and the voltmeter stabilizes above 14v. Then slowly drive until a better temp. Usually 7-10 miles before fully warm.

(high idle in neutral with parking brake on to have trans fluid circulate also)

NJ and Maine climate so winter 0-32 degrees. Negatives are rare.

 

[Dos Perros]

I don't know that you would see any significant increase in transmission fluid temp just idling in park.

It'll warm up enough to burn you in idle. Learned that the hard way changing transmission fluid one time.

 

[Haro450]

If you warm up a newer diesel figure out how to get it into high idle mode. Typically its a series of button touches. It hard on the newer turbos I believe. The high idle get more oil moving.

 

[gbflyer]

Former diesel mech. here. These articles are complete propaganda in my opinion. In cold weather engines absolutely need some warm up time. Even with modern high quality synthetic oils that flow well. Engines are made with several dissimilar metals that all heat and expand at different rates. The best way to avoid damage is slower no load heating of them diesel or gas.

Now modern diesels also have a fine line of warm up time and excessive idle. If you have a diesel made probably 2007 to current deleted or not you need to be utilizing the high idle and the exhaust brake when idling for longer than 5 to 10 minutes. What happens during excessive idle in low ambient temps (sub 40f) is the cylinder temperatures get so low that the diesel burn is incomplete. This results in what is know as cylinder washing. Diesel builds up in the cylinder and leaks past the rings into the crankcase. Extreme issue could be some loss of compression less extreme is fuel dilution of your oil which results in poor lubrication of your engine. If you still have emissions components intact you need to limit idle time even more due to the excessive build up of soot in you egr, turbo, and dpf.

My procedure if my truck hasn't been plugged in all night and its pretty cold is to start it, wait until the automatic high idle kicks in (about a minute) then engage manual high idle to about 1100rpm and engage the exhaust brake which puts a small load on the engine to aid warm up. Then i let it idle until coolant temp is over 100f. At 100f I idle out of the neighborhood and use very light throttle until the coolant temp is above 140f. At 140f if Im not towing I drive fairly normal but I dont use alot of throttle or power until its up to 190f which is normal operating temp. For the love of God please start using winterfronts on your trucks when its below freezing and definitely when its below zero. The best thing you can do for them is get them to operating temp and keep them there as soon as possible. I really cant think of any downsides to them and I dont understand why more guys dont use them. If you are towing and you hear the fan constantly coming on or shes getting hot take it off. If you are unloaded have it on. vent flaps open 32f to 0, closed 0 and below. On diesels idle time after towing or hot weather etc. is just as important. Turbos need to cool down before you shut them down when really hot.

On my gassers I start them let them run about 5 minutes or so and then drive easy until they are to operating temp. Hope this helps.

Agree 100%.

I run a winter front year around on our deleted 6.7 Cummins. It’s never warmer than about 60-65 in the summer here, and the trips are short. I’ve changed to a 190 T-stat. Very bad place for a diesel pickup. The construction gear gets warmed up. The newer stuff limits power until it’s ready.

 

[keilux]

Only if windshield needs de-iced.

 

[Idaho_Potato]

I always warm things up, the only one that has me wondering is newer diesels with intact emissions equipment- idling is no bueno. I still let my superduty warm-up though, It was beat into my head from a young age.

Someone put it in my dad’s head that idling his 2013 Superduty is bad for the emission system. He starts that thing up and will jump on the highway at 15 degrees. I don’t think that can possibly be good for that truck, but so far it seems fine. 180,000 miles.

 

[thinhorn_AK]

Always warm my vehicle up. Can’t see how it would be bad for the vehicle to run. Don’t care if I’m polluting the ozone, and I live in an area where the least of my concerns is someone trying to jack my vehicle at 5am before work

It’s -27 at my house and I just cold started my truck. I’m going to probably let it warm up for at least 30-40 minutes before I head into town.

I’ve seen what oil looks like at those types of temperatures. Not only that, I hate riding in cold vehicles.

 

[RockAndSage]

As a generality, the more modern a vehicle is, the less idle time you need - as long as you're using the proper oil specified by the manufacturer. Proper oil weight especially.

The reason so many modern gas engines use 0W-something oils is because the thinness of that oil gets it distributed quickly throughout the oil system when it's cold - whether that's extreme environmental cold, or just an engine that hasn't been running that day. Oil naturally flows down with gravity when at rest, and away from the friction/bearing surfaces of the motor. So getting it distributed as quickly as possible at startup minimizes the metal-to-metal grind. This is exactly why startup is one of the top two periods where a motor experiences the most wear.

The problem here is that as that 0w oil heats up, if it doesn't have any other kind of additives or engineering, it'll continue to get thinner and thinner, down to the viscosity of water. And the thinner it gets, the worse it gets at lubrication. At best, it'll simply do what honing oils do on whetstones: help transport worn metal particulate away from the friction surfaces.

With modern multi-weight oils, as the 0W heats up, it also thickens up - it has additives in it that are tightly wound long-chain polymers that, as they warm up, they unravel and expand, thickening the oil to a heavier weight as they do so. When you have a 0w-30 oil, for example, the best way to read it would be something along the lines of "Acts like a 0 weight oil when it's cold, thickens up to how a 30 weight performs when it's at operating temperatures."

Before these oils were invented, people had to just run heavier "straight" oils in the summer (because it thins out when it gets hot), and a much lighter oil in frigid temps, just to have oil that was actually liquid, and not acting like frozen honey. In both cases, it resulted in far more engine wear - the thick oil doesn't get to the moving parts fast enough at start-up, and the thin oils don't lubricate well enough once warmed.

A key reality and concept to understand in all of this, is that motors need to have oil at the right viscosity to get the moving parts into what's called the "hydrodynamic lubrication" regime, which is where the parts essentially hydroplane on top of the fluid film, not touching each other at all. The lighter the fluid, the faster the parts have to go to stay on top of that fluid film, just like how you need a certain minimum velocity to get on top of the water when water skiing. This is also why stop-and-go traffic is the other major area where cars experience the most wear-and-tear, besides startup.

The multi-weight oils cover all this - they get oil quickly to bare metal on start-up, then rapidly thicken up to the proper weight that motor needs in order to have its parts running in the hydrodynamic lubrication regime when at full operating temperatures.

All this is a big part of why you don't need as much warm-up time with modern cars, and why higher idling speeds are useful when warming up a very cold engine - and why those automatic idling RPMs go down once the vehicle warms up.

Bottom line for me on warming up modern cars: don't just hop in and go, give it a couple of minutes for that oil's temperature to rise.

For carbureted motors, the engine should be at full operating temps if you don't want it cutting out on you when you try to accelerate.

If we're talking temps below -40F, I'd also strongly consider warming any vehicle up to full operating temps while under a car cover (just be careful of the exhaust pipe) to trap that warm air - specifically to also warm the lubricants in the differentials, bearings in the drive train, and to get the tires up to a more pliable temperature.

 

[RockAndSage]

Here are a couple of pretty interesting videos out of Russia - one's using transparent oil pan and head covers at around -22F/-30C, and shows just how much oil acts like frozen honey in extreme cold, and the other is about the prep needed to start up vehicles at -58F.

The folks up in Alaska and some other parts of the US and Canada know this well, but there's some sort of inflection point at -40F/-40C, where everything just turns into a different world with materials properties and performance. Rubber and metals get brittle, plastics can shatter, differential heating can cause cracks if it happens too rapidly, etc...and everything just takes a lot longer to do safely and competently.

Starting a car at -58F:

Oil behavior in a car at -22F:

I should note that there's no way to know what kind of lubricants they're using - overseas access to high-performance lubricants can be hit or miss, especially in remote areas like these, but it's often surprising what kind of premium performance stuff you can find at times.